As a total Noob where these apps are concerned I'd appreciate some advice. I've checked around the different Open CL threads, but they all seem to refer a lot more to ATI cards rather than Nvidia.

Dumbest question first.
1) Does the ap_cmdline_xxx.txt file syntax need to contain the name of the .exe file or just the switches ? e.g. Should it be AP6_xxx_xxx.exe -s, or just (for example) -v N or -ffa N with each entry ? How should these be entered, one switch per line or consecutively e.g -v N -ffa_block_switch N etc. on the same line

2) What driver version is recommended ? The rig I'm using for test purposes has 285.58 installed but the rig that will be the working rig when testing is complete has 310.70 on board.

3) To save me having to reinvent the wheel, does anyone has some starting values in the settings (-ffa_block, -unroll etc.) for use with a GTS250 and a GTX470 ?

4) What CPU usage should I expect with one core dedicated to the Open_CL app ? If running 2 units per Nvidia GPU, do I still have allow one core per unit ?

As a total Noob where these apps are concerned I'd appreciate some advice. I've checked around the different Open CL threads, but they all seem to refer a lot more to ATI cards rather than Nvidia.

Dumbest question first.
1) Does the ap_cmdline_xxx.txt file syntax need to contain the name of the .exe file or just the switches ? e.g. Should it be AP6_xxx_xxx.exe -s, or just (for example) -v N or -ffa N with each entry ? How should these be entered, one switch per line or consecutively e.g -v N -ffa_block_switch N etc. on the same line

2) What driver version is recommended ? The rig I'm using for test purposes has 285.58 installed but the rig that will be the working rig when testing is complete has 310.70 on board.

3) To save me having to reinvent the wheel, does anyone has some starting values in the settings (-ffa_block, -unroll etc.) for use with a GTS250 and a GTX470 ?

4) What CPU usage should I expect with one core dedicated to the Open_CL app ? If running 2 units per Nvidia GPU, do I still have allow one core per unit ?

2) Driver version really doesn't matter (With the exception that 270 and later drivers use a full core, and that pre-270 drivers use minimal CPU usage, but is slower overall, and you loose the ability to use Cuda42 or Cuda5 apps)

3) There are suggested values at the Bottom of the Readme for the latest AP apps, after that you can tweak it by going up or down on the -unroll (affects memory usage),
or going up or down on the -ffa_block/-ffa_block_fetch values (affects GUI usability, too high and it'll be laggy)
You should find that performance is relatively poor on the GTS250 compared with the Setiathome Cuda apps, and is not worth running on it, and GUI is laggy.

4) Each app instance is going to need a full core available otherwise there will be slowdown (if you're running +270 drivers)